This invention relates to destroying hydrogen peroxide, for example, hydrogen peroxide used in disinfecting lenses, such as contact lenses. In particular, the invention relates to compositions and methods useful to quickly and effectively destroy hydrogen peroxide and disinfect, and preferably clean, such lenses while reducing eye irritation caused by disinfecting the lenses.
Contact lenses should be periodically disinfected and cleaned by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to clean and disinfect his/her contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are hydrogen peroxide disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens. Liquid media (not including the hydrogen peroxide contained therein) used to disinfect contact lenses should be substantially isotonic, for example, to the human eye, and preferably ophthalmically acceptable so as to reduce the chances of problems caused by placing the disinfected lenses in the wearer's eyes.
Catalase, in particular bovine catalase, for example, catalase obtained from beef livers, has been effectively used to promote the destruction of residual hydrogen peroxide contact lens disinfectant. See, for example, Giefer U.S. Pat. No. 4,585,488. While bovine catalase is very useful in this contact lens-related, hydrogen peroxide destruction service, it would be advantageous to employ a still more active and/or stable agent to facilitate the destruction of hydrogen peroxide contact lens disinfectant.
Other catalases, that is catalases obtained from other than bovine sources, are known, for example, as agents useful in decomposing relatively low concentrations (in the parts-per million (ppm) range) of hydrogen peroxide in industrial waste waters. Baker U.S. Pat. No. 2,635,069 discloses catalase obtained from molds, such as Penicillium chrysogenum, Penicillium notatum and Aspergillus niger to decompose hydrogen peroxide under industrial conditions, such as in the manufacture of furs, foam rubbers, textiles, feathers, soaps and foods. Beers, Jr. U.S. Pat. No. 3,123,539 discloses catalase derived from bacterial sources, such as Micrococcus lysodeikticus, as being more active than catalase produced from other sources. This patent does not disclose any specific use for catalase. However, to the present inventors' knowledge, the prior art has not disclosed or suggested the use of any non-mammalian-derived catalase in contact lens disinfecting service.
There continues to be a need for a contact lens care system which rapidly and effectively disinfects, and preferably cleans, a contact lens so that the disinfected lens can be safely and comfortably worn.